Imperial, UCL, King's College - graduate

Hey

I'd like to ask what it's like at UCL, Imperial and King's College. Or jut any universities close to the top that are not Oxford and Cambridge. How tough is the coursework? How many hours a week does one have to study? Is the atmosphere nice? The lecturers, teachers? The students? Do you get those lazy people too? What kind of offers do they make at A-levels? AAA? Do they allow Bs? Because I'm not really familiar with the graduate criteria... I'm an international student, the grades don't translate well into the system of my coutry. We don't get first or second class degrees, we just get a degree, and we have grades of course and GPA, but the numbers are completely upside down relative to the British system and not the same numbers so comparisons are difficult. All I know is: get as good grades as possible if you want to change university for graduate school. Also, is it possible to do there just a Master's degree having a Bachelor's degree from somewhere else or is it rather hard to catch up and the Master's degree is a continuation of the Bachelor's degree and the division is just artificial?